The former Barcelona junior struck in the victory.
Lazio coach Edy Reja remarked: "Keita did very well both attacking and covering, as he worked with real sacrifice for his teammates. If he remains humble, then he can become a great player. We have the talent here, so if the maturity and belief sets in too then we can do well.
"Keita and Lucas Biglia are basically the only new faces here, otherwise it's the same team I left two years ago.
"On Sunday we have Roma in the derby and we want to be even more aggressive and sparky."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball